Abstract:

Embodiments of the present invention are directed to methods and systems
for micromachining a conical surface. In one embodiment, such a system
may include a rotating platform for receiving a long line of laser
illumination, a mask having a predetermined pattern comprising a sector
of a planar ring, the mask being positioned on the rotating platform, a
workpiece stage having a rotational axis for rotating a removably-affixed
workpiece comprising a conical surface, wherein the sector comprises the
planar image of the conical surface, an excimer laser for producing a
laser beam, a homogenizer for homogenizing the laser beam in at least a
single direction, at least one condenser lens, a turning mirror and at
least one projection lens.

Claims:

1. A system for micromachining a conical surface comprising:a rotating
platform for receiving a long line of electromagnetic radiation;a mask
having a predetermined pattern comprising a sector of a planar ring, the
mask being positioned on the rotating platform; anda workpiece stage
having a rotational axis for rotating a removably affixed workpiece
comprising a conical surface, wherein the sector comprises the planar
image of the conical surface.

2-19. (canceled)

20. An application program operational on a computer for enabling a method
for imaging a conical surface of a workpiece, the method
comprising:directing an irradiating beam of electromagnetic radiation at
a mask, wherein the mask includes a planar surface of a sector of a ring
and a predetermined image thereon, the ring sector corresponds to an
unwrapped area of a conical surface of a workpiece;producing, as a result
of the irradiating beam interacting with the mask, an image field for
projection on the conical surface of the workpiece;projecting the image
field onto the conical surface of the workpiece;rotating the mask about
an axis, wherein the axis comprises the center of the ring;synchronously
rotating the workpiece about a second axis, the second axis corresponding
to the conical surface of the workpiece.

[0002]Embodiments of the present invention are directed to methods,
devices and/or systems in the field of micromachining, and more
particularly in the field of laser micromachining.

BACKGROUND OF THE INVENTION

[0003]Laser micromachining is a method by which material is removed from
an object (workpiece) to produce a product, utilizing the laser light
energy. The laser light energy enables the material of the workpiece to
be ablated via either or both of thermal or chemical action.

[0004]Ablating a particular pattern in a workpiece may be accomplished
using mask-projection. In mask-projection, laser light is directed upon a
mask and the image of it then projected onto the workpiece, irradiating
the surface with laser light energy according to the pattern of the mask.
The pattern is reproduced on the surface of the workpiece.

[0005]Although it may be possible to micromachine non-planar surfaces
(e.g., curved surfaces, and the like), such micromachining is difficult
to accomplish at higher speeds/throughputs. Generally, only planar
surfaces are capable of being micromachined quickly using, for example, a
mask-projection system. Thus, it would be an improvement in the existing
laser micromachining systems and methods to be able to laser-micromachine
conical surfaces (for example) in a high speed and efficient manner.

SUMMARY OF THE INVENTION

[0006]Embodiments of the present invention are directed to laser
micromachining apparatuses/systems and/or methods thereof. Specifically,
some embodiments of the invention include a laser micromachining
apparatus for copying an image of a planar mask onto a surface of a
conical workpiece. In one embodiment of the invention, this may be
accomplished by rotating the mask and the cone synchronously.

[0007]Some embodiments of the present invention enable high-speed
machining by projecting a long-line of illumination along a conical
surface all at once with a large-field imaging lens.

[0008]Accordingly, in one embodiment of the invention, a system for
micromachining a conical surface is provided and may include a rotating
platform for receiving a long line of electromagnetic radiation, a mask
having a predetermined pattern comprising a sector of a planar ring, the
mask being positioned on the rotating platform and a workpiece stage
having a rotational axis for rotating a removably-affixed workpiece. The
workpiece may include a conical surface, and the sector comprises the
planar image of the conical surface.

[0009]In another embodiment of the invention, a method for imaging a
conical surface of a workpiece may be provided and may include directing
an irradiating beam of electromagnetic radiation at a mask. The mask may
include a planar surface of a sector of a ring and a predetermined
pattern thereon and the ring sector may correspond to an unwrapped area
of a conical surface of a workpiece. The method may further include
producing, as a result of the irradiating beam interacting with the mask,
an image field for projection on the conical surface of the workpiece,
projecting the image field onto the conical surface of the workpiece,
rotating the mask about an axis, wherein the axis comprises the center of
the ring, and synchronously rotating the conical surface of the workpiece
about a second axis, the second axis being the axis of the conical
surface.

[0010]Embodiments of the present invention are directed to methods and
systems for micromachining a conical surface. In one embodiment, such a
system may include a rotating platform for receiving a long line of laser
illumination, a mask having a predetermined pattern comprising a sector
of a planar ring, the mask being positioned on the rotating platform, a
workpiece stage having a rotational axis for rotating a removably-affixed
workpiece comprising a conical surface, wherein the sector comprises the
planar image of the conical surface, an excimer laser for producing a
laser beam, a homogenizer for homogenizing the laser beam in at least a
single direction, at least one condenser lens, a turning mirror and at
least one projection lens.

[0011]Still other embodiments of the invention may include computer
application programs and computer readable media having an application
program and/or computer instructions provided thereon for controlling
some of the embodiments of the invention for micromachining a conical
surface.

[0012]These and other embodiments, advantages and objects of the invention
will be more apparent with reference with the following detailed
description and attached drawings, a brief description of which is set
out below.

BRIEF DESCRIPTION OF THE FIGURES

[0013]FIG. 1 is a schematic diagram of an optical system for imaging on a
conical surface according to some embodiments of the present invention.

[0014]FIG. 2 is a schematic of the relationship between a planar mask and
a conical workpiece according to some embodiments of the present
invention.

[0015]FIG. 3 is a block diagram of a laser micromachining system according
to some of the embodiments of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016]FIG. 1 illustrates one embodiment of a system 100 according to the
present invention for imaging on a conical surface. As shown, a laser
source 101 directs a laser beam 102 into a beam expander 103. After the
beam expander, the resultant beam may be sent through a homogenizer
and/or condenser lens(es) 104. The homogenizer may comprise those
homogenizers as disclosed in co-owned and co-pending U.S. patent
application publication no. 20040223330, entitled, "Methods and
Apparatuses for Homogenizing Light", the entire disclosure of which is
herein incorporated by reference.

[0017]A field lens 105 receives the homogenized/condensed beam, which
collects the light for illuminating the mask 107. The mask pattern is
preferably a representation of the unwrapped image 202 of a cone, which
corresponds to a conical surface 204 of a cone 206 of a workpiece to be
machined. As shown in FIG. 2, the unwrapped image 202 may be a planar
surface that forms a sector 208 a ring.

[0018]While the present invention is illustrated with the use of a laser,
other devices for generating a beam of electromagnetic energy (e.g.,
x-ray) may also be used with embodiments of the present invention.

[0019]The mask 107 is preferably positioned in an open aperture, motorized
rotary device. The open aperture, motorized rotary device rotates mask
107 about a center of rotation 210 as shown in FIG. 2 (i.e., center of
ring). As shown in FIG. 2, a laser field generated by optics of the
system (i.e., beam expander 103, condenser lens 104 and field lens 105)
may be projected onto the mask 107. The laser field is preferably a
long-line field (i.e., a rectangular field), having short and long axes,
but may comprise other shapes (e.g., elliptical, square, triangular, and
other polygonal shapes). In long-line field embodiments, upon the long
line field encountering the surface for machining, a short axis of the
long-line field may be oriented substantially perpendicular (preferably
perpendicular) to the conical workpiece axis (i.e., the vertex of the
cone 206).

[0020]The long-line field projected onto the mask produces a long-line
laser image field which is then directed, via turning mirror 108, onto
projection lens 109. The projection lens then projects the long-line
image field onto the workpiece, the focusing of which may be accomplished
using adjuster device 110 (e.g., along a "Z" axis). In some embodiments,
the turning mirror may be connected to at least one motor or other
actuator(s) (e.g., piezo-based actuator) familiar to those of skill in
the art, which may enable the mirror to pivot about one or more axes, to
impart other directional control onto the beam. In other embodiments, the
tuning mirror (as well as other components of the optical system) may not
include motor(s)/actuator(s), and may be rigidly affixed in a single
position after setup.

[0021]The focusing adjuster device 110 may comprise a motor (rotary or
linear) (or other actuator device), which may move lens 109 along a
single (preferably) axis (e.g., Z axis). Movement may be established via
a rack and pinion gear arrangement, when using, for example, a rotary
electric motor, or via direct connection of the lens or lens frame to the
forcer or platen of a linear motor.

[0022]The laser image field produced by the projection of the laser light
onto the mask, is then focused on the workpiece 112. Adjuster stages 113
and 114 may be provided (e.g., "X" and "Y" adjuster stages), and may be
initially configured so that the laser image field is projected on the
corresponding area of the workpiece prior to machining. One of skill of
the art will appreciate that in some embodiments of the invention, the
positions of adjusters 113 and 114 need not be adjusted once their
positions are established during an initial setup. In such embodiments,
the conical workpiece need only be rotated about an axis. As shown in
FIG. 1, the axis of rotation of the conical workpiece (for example) is
axis 112a.

[0023]FIG. 3 illustrates a block diagram of some of the embodiments of the
present invention. As shown, a controller may be used to at least one of,
setup, initiate, control and complete the laser micromachining of a
workpiece. The controller may be an analog or digital control device, and
is preferably a computer (e.g., personal computer operating an
application program for controlling one or more of the components of
system 100). For example, the controller may be connected (through either
wireless or wired connection) to at least one of and preferably several
of: the laser/beam source (e.g., power, intensity), and motors/actuators
for: controlling beam expansion or consolidation devices (e.g., beam
expander 103, homogenizer 104, condenser lenses, and the like), the open
aperture-motorized rotary mask stage, the turning mirror 108, the
focusing "Z" adjuster 110, the "X" adjuster stage 113, the "Y" adjuster
stage 114 and the motorized rotary workpiece stage 111. In addition,
position sensors may be positioned on all components and fed into the
controller to provide (preferably) real-time feedback on the positions
and/or status of the components of the system.

[0024]Accordingly, the system may be operable for micromachining a
workpiece upon performing at least several (and preferably all) of the
following: [0025]setup of a workpiece in the motorized workpiece stage
111; [0026]alignment of the adjuster stages 113, 114; [0027]positioning
of turning mirror 108; [0028]positioning of the mask 107 with the open
aperture-motorized rotary stage 106; [0029]positioning of on or more of:
the laser beam 101, the beam expander 103, the homogenizer 104, condenser
lenses and field lens(es); and [0030]focusing of the laser image field
via focusing adjuster 110 such that the laser image field is projected
onto a substantially correct corresponding portion of the conical surface
of the workpiece for machining.

[0031]Accordingly, after initial setup, and after the light source is
switched on, the mask may be rotated around axis 210 while synchronously
rotating the conical workpiece around axis 212. By synchronously rotating
the mask from one side of the ring sector to the other and rotating the
cone around its axis 212, for a full rotation, the entire pattern of the
mask may be imaged to the conical surface of the workpiece.

[0032]In some embodiments, the mask and the workpiece may be rotated in
opposite directions since, in some embodiments, the projection lens
inverts the image of the mask. Thus, if the mask is rotated clockwise,
the conical workpiece is rotated counterclockwise (and visa-versa).

[0033]The homogenizer 104 may include a long line homogenizer to achieve
uniform illumination (see U.S. published patent no. 20040223330).
Although in some embodiments, the depth of focus of the imaging system
and the curvature of the cone may limit the width of the line.

[0034]In some embodiments, the mask pattern may be purposely distorted
with astigmatic distortion--i.e., different magnification in the X and Y
directions along the conical axis to account for the variable radius
along the conical surface. Alternatively, instead of creating the
purposeful distortion on the mask, the optical/projection system may also
create a similar astigmatic distortion to achieve the same result.

[0035]To that end, with regard to the above-noted embodiments, it is
preferable that the long line of illumination include a narrow line--if
the illumination line is too wide (according to some embodiments), the
astigmatic distortion intentionally created by the mask or by the optics
may blur the image on the workpiece. Thus, illuminating only a
sufficiently narrow line effectively eliminates the effect of the
astigmatism. For example, when machining a conical workpiece of about 25
mm in size, having conical surface of about 20 mm in length and having
diameters of about 2 mm and about 10 mm, a width of a narrow line may be
about 1 mm.

[0036]However, the mask and the workpiece in some embodiments may be
imaged without astigmatism distortion. In such embodiments, the
magnification values are preferably the same in both the X and Y
directions. Therefore, when both the mask and the workpiece are rotated,
the illumination line may be wider, and the illumination width is only
limited by depth of focus on the curved surface. Thus, the process for
these embodiments may be faster by rotating both the mask and the
workpiece.

[0037]Having now described a few embodiments of the invention, it should
be apparent to those skilled in the art that the foregoing is merely
illustrative and not limiting, and it should be understood that numerous
changes in creating and operating such systems and methods may be
introduced without departing from the true spirit of the invention as
defined in the appended claims.